1. Field of Invention
The present invention relates to a translucent reflection type electro-optic device, an electronic instrument therewith, and a method of fabricating a translucent reflection type electro-optic device. In particular, the present invention relates to a pixel configuration of a translucent reflection type electro-optic device.
2. Description of Related Art
Electro-optic devices, such as liquid crystal devices, are used as direct-viewing display devices of various instruments. Among the electro-optic devices, for instance, in an active matrix type liquid crystal device that uses a thin film transistor (TFT) as a pixel switching non-linear element, as shown in FIGS. 16 and 17, of a TFT array substrate 10 and an opposite substrate 20 that interpose a liquid crystal 50 as an electro-optic material, on the TFT array substrate 10, a pixel switching TFT 30 and a pixel electrode 9a that is made of a transparent conductive film such as an ITO film electrically connected to the TFT 30 can be formed.
Furthermore, of the liquid crystal devices in a reflective type, in order to reflect an ambient light incident from a side of the opposite substrate 20 toward the opposite substrate 20, a light reflection film 8a is formed on a bottom layer side of the transparent pixel electrode 9a. As shown with an arrow mark LA in FIGS. 17 and 18, the light that enters from the opposite substrate 20 side is reflected by the TFT array substrate 10 side, and a light that exits from the opposite substrate 20 side displays an image (reflection mode).
However, in the reflective type liquid crystal device, when directionality of the light reflected from the light reflection film 8a is strong, remarkable dependency on an angle of field, such as brightness, is different depending on an angle of viewing an image is caused. Accordingly, at the fabrication of a liquid crystal device, on a surface of an interlayer insulating film 4 or of a surface protection film (not shown) formed thereon, a photosensitive resin, such as acrylic resin, is coated in a thickness of 800 to 1500 nm. Thereafter, by use of photolithography of a bottom layer side of the light reflection film 8a in a region that overlaps with the light reflection film 8a in plane, a convexity and concavity formation layer 13a made of the photosensitive resin is selectively left with a predetermined pattern. Thereby, a surface of the light reflection film 8a is endowed with a concavity and convexity pattern 8g. In addition, since, in this state as it is, edges of the concavity and convexity formation layer 13a appear as it is in the concavity and convexity pattern 8g, another layer, a top layer insulating film 7a made of a photosensitive resin layer higher in fluidity, is coated and formed on a top layer of the concavity and convexity formation layer 13a, and thereby the surface of the light reflection film 8a is endowed with a concavity and convexity pattern 8g that is edgeless and formed in a smooth shape.
Furthermore, among the reflective liquid crystal devices in a translucent reflection type liquid crystal device that can display even in transmission mode, in the light reflection film 8a, in a region that overlaps with the pixel electrode 9a in plane, a light transmission window 8d is formed. So far, for instance, as shown in FIG. 16, one light transmission window 8d has been formed in rectangle for each pixel. In a region corresponding to the light transmission window 8d, the concavity and convexity formation layer 13a is either entirely formed or not at all formed, resulting in a flat surface.
In the translucent reflection type liquid crystal device thus configured, when a backlight device (not shown) is disposed on a side of the TFT array substrate 10 and a light exited from the backlight device is entered from the side of the TFT array substrate 10, as shown with arrow marks LB1 and LB2 in FIG. 18, a light proceeding to the light reflection film 8a is intercepted with the light reflection film 8a and does not contribute in the display. By contrast, the light proceeding to the light transmission window 8d where the light reflection film 8a is not formed, as shown with an arrow mark LB0 in FIGS. 17 and 18, transmits through the light transmission window 8d to the opposite substrate 20 side, resulting in contributing in the display (transmission mode).
However, in the existing translucent reflection type liquid crystal device, a display light amount in the reflection mode and that in the transmission mode are completely provided by areas of the light reflection film 8a and the light transmission window 8d. Accordingly, when the brightness of one display mode is heightened, that of the other display mode is sacrificed, resulting in a problem of difficulty in improving the brightness in both modes.
In view of the above problems, the present invention intends to provide a translucent reflection type electro-optic device that can increase a display light amount in both reflection mode and transmission mode, an electronic instrument therewith, and a method for fabricating a translucent reflection type electro-optic device.
In order to overcome the problems, the present invention can provide, a translucent reflection type electro-optic device including, on a substrate that holds an electro-optic material, a concavity and convexity formation layer made of a first light transmitting material formed in a predetermined pattern, a top layer insulating film made of a second light transmitting material formed on a top layer side of the concavity and convexity formation layer, a light reflection film formed on a top layer side of the top layer insulating film, and a light transmitting electrode formed on a top layer or a bottom layer of the light reflection film at a top layer side of the top layer insulating film. Further, a light transmission window can be partially formed in the light reflection film, and wherein the light transmission window is plurally formed at positions each of which overlaps with at least part of a plurality of convexities that forms the concavity and convexity formation layer, or with at least part of plurality of concavities. Additionally, each of the first light transmitting material and the second light transmitting material has a refractive index that endows an interface between the concavity and convexity formation layer and the top layer insulating film with a lens function that refracts a light entered from a back surface side of the substrate toward the light transmission window.
Furthermore, in the present invention, a method of fabricating a translucent reflection type electro-optic device that includes, on a substrate that holds an electro-optic material, a concavity and convexity formation layer made of a first light transmitting material formed in a predetermined pattern, a top layer insulating film made of a second light transmitting material formed on a top layer side of the concavity and convexity formation layer, a light reflection film formed on a top layer side of the top layer insulating film, and a light transmitting electrode formed on a top layer or a bottom layer of the light reflection film at a top layer side of the top layer insulating film. Further, a light transmission window is partially formed in the light reflection film. The method including plurally forming the light transmission window at positions each of which overlaps with at least part of a plurality of convexities that forms the concavity and convexity formation layer, or with at least part of a plurality of concavities. Further, the method can include using, as the first light transmitting material and the second light transmitting material, transparent materials having different refractive indices, and thereby endowing an interface between the concavity and convexity formation layer and the top layer insulating film with a lens function that refracts a light entered from a back surface side of the substrate toward the light transmission window.
In the translucent reflection type electro-optic device thereto the present invention is applied, since there is formed the light reflection film, a reflection mode display can be performed, and since the light transmission window is partially formed in the light reflection film, a transmission mode display can be also performed. Here, on a bottom layer side of the light reflection film, the concavity and convexity formation layer is formed with the first light transmitting material to endow the surface thereof with the concavity and convexity pattern, and on a top layer side of the concavity and convexity formation layer a top layer insulating film made of the second light transmitting material is formed. Accordingly, in the present invention, as the two light transmitting materials, ones having different refractive indices are used, and the light transmission window is formed at a position that overlaps with concavities or convexities that constitute the concavity and convexity formation layer, and thereby the lens function that refracts a light entered from a back surface side of the substrate toward the light transmission window is endowed to an interface between the concavity and convexity formation layer and the top layer insulating film. Accordingly, of the light entered from the back surface side of the substrate, a light that proceeds toward the light reflection film and does not so far contribute in the transmission mode display can contribute in the display by partially transmitting the light transmission window. Accordingly, without enlarging an area of the light transmission window, a display light amount in the transmission mode can be increased. As a result, without sacrificing the brightness in the reflection mode display, the brightness at the transmission mode can be improved.
In the present invention, the light transmission window, in some cases, is formed, for instance, at a position that overlaps with at least part of the convexities of the plurality of the convexities. In such a case, the convexity is formed into a convex lens shape that swells upward with roundness, and as the first light transmitting material a light transmitting material having a refractive index larger than that of the second light transmitting material is used.
In the present invention, when the plurality of the convexities is formed into a convex lens shape that swells upward with roundness, after the concavity and convexity formation layer is formed into a predetermined pattern with, for instance, a light transmitting photosensitive resin as the first light transmitting material, the photosensitive resin is heated and melted.
Furthermore, in the present invention, the light transmission window can be formed at a position that overlaps with at least part of the concavities of the plurality of the concavities. In this case, the concavity is formed into a concave lens shape that dents downward with roundness, and as the first light transmitting material a light transmitting material having a refractive index smaller than that of the second light transmitting material may be used.
In the present invention, when the plurality of the concavities is formed into a concave lens shape that dents downward with roundness, after the concavity and convexity formation layer is formed into a predetermined pattern with, for instance, a light transmitting photosensitive resin as the first light transmitting material, the photosensitive resin is heated and melted. In the present invention, as the first light transmitting material and the second light transmitting material, for instance, a light transmitting photosensitive resin can be used.
In the present invention, the light transmitting electrode is preferably formed on a top layer of the light reflection film. When thus configured, only by forming an opposite electrode of the opposite substrate and a transparent pixel electrode from the same light transmitting material, the electro-optic material can be hindered from polarizing and orientating. In the present invention, the electro-optic material is, for instance, liquid crystal.
Furthermore, a translucent reflection type electro-optic device according to the present invention can include, on a substrate that holds an electro-optic material, a concavity and convexity formation layer made of a first light transmitting material formed in a predetermined pattern, a top layer insulating film made of a second light transmitting material formed on a top layer side of the concavity and convexity formation layer, a light reflection film formed on a top layer side of the top layer insulating film, and a light transmitting electrode formed on a top layer or a bottom layer of the light reflection film at a top layer side of the top layer insulating film. Further, a light transmission window is partially formed in the light reflection film and the light transmission window is plurally formed at positions that overlap with at least part of a plurality of convexities that the concavity and convexity formation layer forms, or with at least part of a plurality of concavities. Each of the first light transmitting material and the second light transmitting material has a refractive index different from each other.
Accordingly, by arbitrarily selecting the refractive index among a light entered from a back surface side of a substrate, a light that proceeds toward the light reflection film and does not formerly contribute in the transmission mode display can be arbitrarily controlled in its refractive index. Accordingly, the light partially transmits the light transmission window and can contribute to the display. As a result, since without enlarging an area of the light transmission window, the display light amount in the transmission mode can be increased, without sacrificing the brightness in the reflection mode display the brightness in the transmission mode can be improved.
The electro-optic instrument that the present invention is applied can be used as a display device of an electronic instrument, such as mobile computers or portable telephones.